A classic paper that informed us, years ago, that orthodontic extractions do not harm facial profiles!
Not too long ago, orthodontists realized that extraction therapy had an impact on the facial profile of the patients. This apprehension has opened the floor for many major conflicts and ever since then, the extraction of teeth in orthodontics has been a matter of fierce debate.
In orthodontics, the practice of tooth extractions has been widely accepted as a coadjuvant for a variety of different procedures. But recently, non-extraction treatments have been gaining widespread momentum. The risk of condylar displacement, narrowed smiles, and ‘dished-in’ profiles associated with extractions have deterred many clinicians from this old practice.
Extractions can cause significant changes in the facial profile, and therefore, it is crucial for clinicians to fully comprehend the effects of different treatment options for the patient. This study examines the differences between extraction and non-extraction treatments and weighs the upsides between them.
This study was conducted by a team from the USA and published by the American Journal of Orthodontics & Dentofacial Orthopedics (AJO-DDO).
A long-term comparison of non-extraction and premolar extraction edgewise therapy in
“borderline” Class II patients.
D Paquette, J Beattie, L Johnston.
AJO-DDO 1992; 102:1-14
doi.org/10.1016/0889-5406(92)70009-Y
What they asked
The authors aimed:
“To compare non-extraction and premolar extraction edgewise therapy in patients with borderline Class II malocclusion.”
What they did
They carried out this study in several stages:
- They tried to contact cases that were inherent to Class II division I first premolar extraction and non-extraction cases that had been treated at St. Louis from 1969 to 1980. These individuals were approached to take part in the study. Only 1 out of the 9 possible patients accepted this invitation.
- Next, they collected data from the patient’s initial cephalograms and study models. They used a statistical technique called discriminant analysis to group samples of patient records together based on their characteristics.
- They used this data to identify a sample of patients who could have been treated with or without extractions.
- Lastly, they contacted 48 extraction and 48 non-extraction patients. Their final sample was a total of 30 non-extraction and 33 extraction patients. These patients were called in for cephalograms, study models, and self-assessment of the profile aesthetics.
The authors carried out an extensive analysis of the data with individual comparisons across multiple cephalometric variables.
What they found out
They discovered the following findings:
- 73% of the extraction and 57% of the non-extraction cases had crowding of less than 3.5 mm.
- The patients showed a preference for neither the non-extraction nor the extraction profile.
- Non-extraction patients had lips that were 2 mm more procumbent than those who had extraction treatment.
They made valid points in their findings and emphasised the fact that there were no differences between the effects of extraction and non-extraction treatments.
My thoughts
A great place to start analysing this study is to remember that this paper came out almost 24 years ago and as one would expect, our knowledge of research techniques and statistical analysis has obviously changed.
Considering this study to be a classic, there are a few important points to discuss about it:
- The initial sample of patients that were analysed was 238 out of almost 2142 patients. Thus, we must bear in mind that those who were included in the study were different from those who responded to the invitation. This increases the chance for selection bias.
- The dropout rates from the final sample were also quite high. Additionally, 33 of them could not attend for records.
- Fortunately, they managed to include a group of patients who closely resembled the other group apart from the decision to extract or not to extract.
From these points, we can extrapolate that there was a high degree of uncertainty in the treatment decision, however, we do not know the exact calibre and direction of said bias.
Final thoughts
Overall, this paper provided us with a good amount of evidence. For a sample of borderline Class II patients, the decision either to extract or not to extract can play a clinically significant role in the treatment process.